1. Field of the Invention
The present invention relates to novel substituted acetamide derivatives and more particularly, to substituted acetamide derivatives which are useful in the medical field, particularly in the field of treatment for and prevention of hypercholesterolemia, hyperlipemia and arteriosclerosis, as well as use thereof.
2. Related Art Statement
In recent years, it is pointed out that an incidence frequency of arteriosclerosis and various coronary and cerebro-arterial diseases accompanied thereby has been increasing. A variety of factors are considered as causes for arteriosclerosis but one of the major factors is an increased cholesterol level in blood. Thus, many cholesterol lowering agents have been developed for the purposes of prevention of and treatment for arteriosclerosis and a part of these hypocholesterolemic agents have also been employed in the clinical field. Cholesterol in vivo is maintained on a certain level by uptake from an outside source through diet and internal biosynthesis. Among them, cholesterol in diet is absorbed in the form of free cholesterol, esterified by the action of acyl-coenzyme A: cholesterol O-acyltransferase (ACAT) and released in blood as a chylomicron. It is thus expected that inhibition of ACAT would prevent absorption of cholesterol from intestine and reduce cholesterol level in blood. On the other hand, atherosclerosis is a disease caused by accumulation and thickening of cholesterol esters in the arterial wall. It is known that the formation of the cholesterol esters is catalyzed by ACAT. Therefore, inhibition of ACAT would result in prevention of the formation and accumulation of cholesterol esters, which would lead to suppression of advancement in arteriosclerosis and its prevention.